Controller for electric motors



July 26, 1927. 1,637,054

E. w. SEEGER CONTROLLER FOR ELECTRIC MOTORS Filed Sept. s. 1925INVENTOR.

WM WWW)! ATTORNEY fects restarting without the Patented July 26, 1927.

' UNITED STATES PATENT OFFICE.

EDWIN W. SEEGER, 0F MILWAUKEE, WISCONSIN, ASSIGNOR TO THECUTLII]R-llI-IAIVI MER MFG. 00., 0F MILWAUKEE, WISCONSIN, A CORPORATIONOF WISCONSIN.

CONTROLLER FOR ELECTRIC MOTORS.

Application filed September 5, 1925.

This invention relates to controllers for electric motors, and moreparticularly to motor starters of the C. E. M. F. type.

Motor starters of the aforesaid type usually include anelectro-responsive main switch for controlling the power connectionsofthe motor and one or more .electro-responsive switches for excludingsteps of resistance in the motor circuit. The main switch is usuallypush button controlled, and in responding is adapted to maintain itselfin closed position through the medium of auxiliary contacts associatedtherewith while the accelerating switches are provided with operatingwindings connected across the motor armature to render the sameresponsive to given counter voltage conditions in the armature circuit.In practice itjhas been found that upon interruption of the motorcircuit by the main switch the accelerating switches usually remain inclosed position until the motor is practically stopped, whereby.reclosure of the. main switch prior to stopping of the motorefprotective accelerating resistance in circuit.

The present invention has among its objects to provide a motor starterof the C. E. M. F. type having means associated therewith for insuringinclusion of the accelerating resistance immediately upon interruptionof the power connections for the mo tor. Y i

Another object is to provide a motor starter of the aforesaid characterincluding means controlled by the auxiliary maintaining contacts of'themain switch for insuring inclusion of the accelerating resistanceimmediately upon opening of said main switch. I

Various other objects and advantages of the invention will hereinafterappear.

The accompanying drawing diagrammatically illustrates an embodiment ofthe invention which will now be described, it being understood that theembodiment illustrated is susceptible of modification without departingfrom the spirit and scope of the ap pended claims.

Referring to the drawing, the same illustrates a compound wound motor Mhaving an armature A, a series field winding F and a shunt field windingF Motor M is adapted to be connected across lines L-L a switch 2 isprovided for fully described. Closure ,to" prevent closure of Serial No.54,641.

by an electro-responsive main switch 1,. and

of accelerating resistance circuit.

The operating winding 1 of main switch 1 1S controlled through themedium of a normally open starting push button '3 and a normally closedstop push button 4, and said mam switch is also providedwith' auxllrarycontacts l for establishing a maintaming circuit therefor upon releaseof push button 3. provided with two operating windings 2 and 2*, and,for purposes hereinafter set forth, said windings are connected tooppose each other under certain conditions and to act cumulatively underother con ditions.

The function and operation of the aforedescribed controller, togetherwith the circult connections therefor will now be more of push button 3establishes an energizing circuit for main switch 1 extending from lineL through. push buttons 3 and 4, by conductor 5 to and through theoperating winding 1 of switch Land by conductor 6 to line L Closure ofpush button 3 also establishes circuit from line L through said pushbutton, by conductor. 7 through operating windings 2" and 2, byconductor 8 through the. field F, by conductor 9 through resistance R toline However, windings 2" and 2 are so arranged that when the same areconnected in the aforesaidmanner theyact in opposition switch 2. Uponclosure of switch 1 the motor is Y connected across lines L and Lthrough resistance R and upon release of push button 3, switch 1maintains itself in closed position by a circuit extending from line L,by conductor 10 to and through the auxiliary contacts 1', by conductor 9to and through the operating winding 2 by conductor 7 through pushbutton 4,by conductor 5 to and through the operating winding 1 and byconductor 6 to line L Also,upon closure of switch 1 and release of pushbutton 3, the auxiliary contacts 1 connect the winding 2 across theterminals of the armature A to render the current in said windingdependent upon the G. E. M. F. of the motor armature. Windings 2* and 2then act cumulatively, and, when the C. E. M. F. of the motor armaturerises R in the motor excluding a step c Accelerating switch '2 is to agiven value, windings 2 and 2" effect closure of switch 2 for exclusionof resistance R in the motor circuit.

Opening of push button a interrupts the aforedescribed maintainingcircuit for switch l and'said main switch in opening immediatelydisconnects the winding 2 from the motor circuit to insure opening ofaccelerating switch 2.

The controller thus functions to prevent restarting of the motor withoutthe accelerating resistance R in circuit therewith, and it'should benoted thatdue to connection of the windings 2 and 2 ofthe acceleratingswitch in the manner aforedescribed the controller functions without'theuse of auxiliary control contacts other than those which are usuallyemployed for establishing a maintaining circuit for the main switch.Further it should push button 3 is held in closed position switch 2 isrendered unresponsive, whereby opening and reclosure of push button +1provides forinching operation of the motor at slow speed.

WhatI claim as new and desire to secure by Letters Patent is:

1. In a motor control system, the combination with an electric motor, ofan-electroresponsive line switch for controlling the circuit of saidmotor, an electro-responsive accelerating switch for said motor, meansfor controlling the energizing circuit of said line switch andfor'alsoestablishing a maintaining circuit therefor upon closurethereof, and a plurality of operating windings associated withsaid'accelcrating'switch and controlled by said means to provide fordelayed closure of said accelerating switch upon closure of said mainswitch and for immediate opening of said accelerating switch uponopening of said main switch.

'2. In a motor control system, the combination with an electric motor,of an elect-roresponsive line switch and an accelerating switchtherefor, control means for said line switch including auxiliarycontacts for establishing a maintaining circuit therefor upon closurethereof, a plurality of operatbe noted that as long as ing windingsassociated with said accelerating switch and circuit connections betweensaid windings and said auxiliary contacts providing for connection ofone of said windings. in the motor circuit upon closure of said lineswitch and for connection of the other of said windings in themaintaining circuit of said line switch upon closure of the latter, saidwindings when so connected being adapted to act cumulatively to effectclosure of said accelerating switch.

3. In a motor control system, the combination with an electric motor, ofan electroresponsive line switch therefor, control means for said lineswitch including auxiliary contacts associated therewith forcstablishing a maintaining circuit therefor upon closure thereof and anelectro-rcsponsive accelerating switch having a plurality of operatingwindings, one to be connected, by said contacts, across a portion of themotor circuit and the other to be connected, by said contacts, in seriesin the energizing circuit of said line switch, said windings when soconnected being adapted to act cumulatively to effect closure of saidaccelerating switch under given electrical conditions in the motorcircuit.

4. In a motor control system, the combination with an electric motor, anelectroresponsive line switch for controlling the circuit of said motor,a normally open and a normally closed push button in the energizingcircuit of said line switch, the former being adapted to establish anenergizing circuit for said switch through the latter, auxiliarycontacts associated with said line switch for establishing a maintainingcircuit therefor through the medium of said normally closed push button,and an accelerating switch having a plurality of operating windings, oneto be connected in shunt with the motor armature by said auxiliarycontacts and the other to be connected in series in the maintainingcircuit of said line switch by said auxiliary contacts.

In witness whereof, I have hereunto subscribed my name.

EDWIN W. SEEGER.

